step 1) drop the tile.
step 2) reach the LEFT side
step 3) inch all the way to the edge by careful stepping.
step 4) turn around.
step 5) start to run left
step 6) immediately move right to turn around on a run. You will turn without bumping the wall if you reverse fast enough on an accurate port.
step 7) hold jump button after turning around. Having done this you will barely clear the gap, having done a flawless 2 tile running jump.

There are two possible failures to this test.

1) bump the wall. this means turning fast enough was impossible, or that the collision is off.
2) not bump the wall, but fail to jump. this means 2 tile running jump simply doesn't work. because there is more space on the right side, the test is pointless to run from there. but there is BARELY enough space on the left side to test the 2 tile running jump.

the running jump should be impossible if you start running from the left wall, because without reversing, you need 3 tiles of space to do a running jump.

Note that 2 tile running jump is not required in original POP. it's an optional technique. SO ports that don't allow it can still be beaten. But i'm pretty sure many mods do require it.

The vga graphics on the DOS version are about perfect. Not too cartoony, not too realistic, they look just right. No vanity and no superfluous, cluttering details either, yet is dullness effectively avoided through a variety of rather fitting color schemes.

The sound samples, you can't beat them! unlike most of the junk from the day, POP1's don't even clip.

Music-wise, the OPL synth offers a wonderful, enchanting, atmospheric theme still unmatched to this day.

Anyway about my test. the ONLY way to perform the running jump across that drop from screen one to screen two is to inch up to the gap, then two tile running jump. On all perfect versions of the game, it works, from both sides.

If you can make the running jump from the wall, then the conversion is too easy.

If you hit the wall, then wall collision detection is off.

If you don't hit the wall, but can't make the jump, then two tile running jump is broken, and this breaks many speedrunning tricks.

The other test is to see if guards turn around when you step carefully beneath or above them. they should only turn around when they hear your footsteps or wall bumping, or you reach their level, giving you time to whip out your sword after climbing or dropping down. If this test passes as well, the conversion can be assumed perfect. There are a few esoteric tricks involving gates and/or guards, and one silly bug with jumping and hanging at the bottom of the screen as well, but even without these features, the conversion can be assumed to be still perfect. if these ones are replicated too, and fake spike tiles can be placed, then it is mod perfect.

Norbert wrote:A couple of days from now I'll write a bit more about the differences between the DOS and GBC ports.

These are some of the things I noticed while working on my Game Boy Color level editor (legbop):
- The GBC prince has a dark skin color. This makes sense, it's Persia (Iranian area) after all. However, I only realized this when I had already worked on the level editor for a week. The DOS prince is 'white'. The Apple II prince is... a darker shade of orange. If you wanted high contrast and a stereotypical skin for a white person, for instance when a child uses a coloring book or for a cartoon - or game, I can see how a white person's skin would be orange (or dark orange, suntanned perhaps). Anyway...
- In the GBC version, palace potions show up higher than dungeon potions. The position of palace chomper blades is also not the same as dungeon chompers.
- Event information is stores in a from-room/tile to-room/tile fashion. This means buttons can both open and close gates/doors at the same time. It also means a close button can open, and vice versa. Buttons have event numbers, always even (never odd), but these are being ignored.
- As you know, after merging with your shadow in level 12, you walk on tiles that are invisible until you touch them. In the GBC version, these tiles are part of the level data. This means you can use them everywhere you want.
- The mirror on the other hand is not part of the level data, which means you can not use it wherever you want.
- When looking at the starting positions of guards, some of them are not facing in the right direction. See, for example, room 3 of level 1. This is not a problem though, because guards instantly turn around if the prince is on their row.
- Potions have no bubbles. The prince cannot tell potions apart.
- Palace levels have no wall shadows/lines/patterns.
- Palace balconies do not show up.
- If there is no room above the current room, the game displays floor tiles there and not wall tiles. This makes it seem as if there is a room above the current room.
- Gates with tiles to the left add floor shadows.
- In level 12b, you start on room to the right.
- Level 3 has no checkpoint.
- The training level is actually two levels. When the prince walks into the room with the sword, the game loads the the second level.
- A 'various' level is used to show the training door, the continue (password) room, the princess rooms (inside and to left), and language room. This also means it sometimes uses dungeon tiles, sometimes palace tiles.
- Level 6 does not have a fat guard.
- Here and there, room links - numbers above 24 - are used to load other levels. These cause broken room links, among other things. Level 6, where the prince falls into level 7. Level 12a, where the prince walks into the level with Jaffar. Level 12c, where the prince enters the princess room. The training levels, because it simulates a save point as described above.
- I'm unsure if guards have differing skills. The first guard in level 8 feels as easy as the others.
- All tapestries are the same.
- The prince can stand on the edges in front of closed gates.
- The mouse looks up in the end cinematic (the embrace), but not in level 8.
- Wall shadows behind pillars do not show up. See, for example, room 1 of level 1.
- The game does not give a password after level 6.
- Loose tiles wobble on floors, but not when the prince touches the ceiling.
- Merging with the shadow in level 12a does not give an extra life.
- The princess room at the very end seems to be a static image. I wonder why it's not using the rooms of the 'various' level there.
- The floating prince does not move forward. Unfortunately, this limits modding possibilities.
- Several things either do not show up or do not show up properly depending on tiles around it. One clear example is the left section of level doors: almost anything to the left messes it up. Another example are wall shadows and rubble: they do not show up without other tiles around them.
- When landing on loose tiles, the prince can walk on them, turn around, and even jump up.
- The spikes are on the left side of tiles. As a result, if a floor only has spikes, the prince can still land on it, namely at the very right near the wall.
- After a running jump, the GBC prince can stop much faster than the DOS prince. Do this by pressing down after the jump.
- The prince also moves the same horizontal distances, from tile edge to tile edge. A small step is 1 tile, walk forward is 2, a running jump is 3. This means the prince is never misaligned. One exception, see below.
- The prince gets misaligned if he sheaves (puts away) his sword with a wall to his right. This causes various things to happen, including buttons that appear in strange places, inability to climb tiles, etc.

I'm sure there's more, but these are some of the things that I noticed about the GBC version.

If I recall correctly, the top bit is 1 for these (which means that exiting the room that way will load the next level), and the bottom 7 bits store the actual room number.

Norbert wrote:
- The game does not give a password after level 6.

I guess it would have been a bit strange to interrupt the fall.

Norbert wrote:
- A 'various' level is used to show the training door, the continue (password) room, the princess rooms (inside and to left), and language room. This also means it sometimes uses dungeon tiles, sometimes palace tiles.

For editing this level, it would be convenient if I could jump into any room, not just the adjacent ones.

David wrote:For editing this level, it would be convenient if I could jump into any room, not just the adjacent ones.

I get what you mean. For now, it should still be fairly straightforward to fix broken room links (on the room links screen, click 5 times on the square right of 8), then attach rooms or simply select one of the new quick layouts at the bottom. For instance the vertical layout, if you just want to scroll wheel through the rooms on the main screen.

It seems that, in proportion, more console ports fail the tests than computer ports.
I wonder if there is any reason for this.
Maybe it was easier to port the C source of the DOS version to computers than to consoles?